The present invention relates to a papermakers dryer fabric adapted to carry a paper web on one fabric surface thereof and woven from machine direction and cross machine direction yarns wherein the yarns cross over each other to create void volume both inside the structure of the fabric and at the surfaces of the fabric.
Generally speaking papermaking machines are made from up to three sections, namely forming, pressing and drying sections. By the time the paper web enters the drying section from the pressing section, as much as fifty percent of the water has been removed from the paper web. The remaining water removal is then completed in the dryer section. Here the paper web is carried by dryer fabrics transferring the paper web in succession from one to another of the rotating surfaces of sections of steel cylinders arranged along the length of the machine which are heated by high pressure steam.
The so far known papermakers dryer fabrics have the disadvantage that contaminants from the paper making process become trapped within the fabric structure. This reduces the permeability and effectiveness of the fabric: both sheet runnability and tail feeding are adversely affected due to reduced transmission of under pressure through the fabric to the paper web. Drying efficiency and uniformity of drying are adversely affected due to contaminants making the fabric surface uneven, or the lower permeability reduces ventilation and extraction of air/water vapour during the drying process.
High pressure water showers can be used to loosen the contaminants and remove them within the flow of water to a “save all” tray or by suction at an extraction zone. If the fabric is dirty then the papermaker can increase the water pressure. However too much water to clean the fabric will cause the fabric to run wet causing uneven moisture profiles and wet streaks in the paper. The removal of the water and contaminants is also difficult because the water and contaminants are held within the voids of the fabric structure.